Apparatus and method to increase the air flow in a fireplace

ABSTRACT

This invention relates generally to a fireplace having a firebox chamber exhausting upwardly to a chimney, a front opening and fuel positioned in the firebox chamber and more specifically to an easily removable cover apparatus for the upper portion of the front opening whereby air flowing through the front opening will predominately flow through the lower portion of the firebox which increases the air flow onto the fuel.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates generally to a fireplace having a fireboxchamber exhausting upwardly to a chimney, a front opening and fuelpositioned in the firebox chamber and more specifically to an easilyremovable cover apparatus for the upper portion of the front openingwhereby air flowing through the front opening will predominately flowthrough the lower portion of the firebox which increases the air flowonto the fuel.

[0003] 2. Description of the Prior Art

[0004] One of the more important issues to be addressed in fireplacedesign or fireplace tools and devices is how to get the maximum amountof air (i.e. oxygen) to the fuel (eg wood, coal, peat and so forth).This issue of maximizing air flow to the fuel is especially importantduring the initial stages of starting a fire. For a standard residentialfireplace it is not as important once a fire is well underway in thefireplace. This is because most residential fireplaces are obviouslydesigned such that once the fuel is fully burning they draw quite well,burn efficiently and do not require additional means or structures tofocus air flow on the fuel.

[0005] In the past, the issues of maximizing air flow on the fuel at theearly stages of the fire have been addressed by both (1) the design ofthe fireplace or fireplace openings to increase the airflow over thefuel, and (2) by the use of tools or methods to direct air on the fuelby manually blowing, fanning or pumping the air to the fuel (e.g.diaphram blowers or methods as simple as fanning the fuel withmagazines).

[0006] In most commercial situations or in residential situations whereaesthetics is not an issue (i.e. the primary means of heating the homeis the fireplace) these problems are typically solved by focusing theairflow onto the fuel by means such as restricting openings, dampers anddeflectors. These methods result in fires which are easily started andefficient but almost by definition they are not as aestheticallypleasing since they necessarily involve in some way restricting theopening to the fireplace. In other words, what you gain in ease ofstarting and efficacy you give up in aesthetics since one can't see thefire burning in the fireplace as well as one can see the fire with anunobstructed view

[0007] Examples of such fireplace designs to increase the oxygen/airflow over the fuel includes the following patents:

[0008] The Brown patent (U.S. Pat. No 4,173,967) discloses a grate whichhas orifices which force the air to flow toward the center of the grateto maximize combustion in this area.

[0009] The Wilkening patent (U.S. Pat. No 4,706,647) discloses an airflow damper-director control which controls the flow of air to fire fromopenings disposed in the fireplace enclosure.

[0010] The Shults patent (U.S. Pat. No 2,814,287) for draft controlshows and adjustable deflector used with seperate damper controls overopenings in the front of fireplace to control the direction and amountof air flow.

[0011] The Merryweather patent (U.S. Pat. No. 2,707,946) shows astationary deflector for directing the air flow from an adjustabledamper which controls the flow of air from openings in the front of thefireplace enclosure.

[0012] The Lydle patent (U.S. Pat. No. 3,459,173) discloses a fireplacefront or screen with a plurality of openings that are connected to achamber with a damper which allows air flow in one direction and adeflector that is always open that deflects air in another direction.

[0013] These strucural examples all have the additional disadvantages(in addition to not being aesthetically pleasing) of being relativelycomplicated from a structural point of view and also they are typicallybuilt into the structure of the fireplace, grates or fireplace openings.This permanence of the structure means that it is normally still thereafter the fire is self perpetuating (i.e. with sufficient fuel willremain burning without additional human intervention such as fanning theflames or adding combustible materials such as newspaper or lighterfluids). Lastly, the prior art structural solutions above requireretrofitting of the existing fireplace, grates or fireplace openings.This can be expensive, time consuming, and complicated.

[0014] What is needed is a simple, inexpensive, cover apparatus which iseasily mountable and easily removable from the front entrance of afireplace to focus the air flow on the fuel. This mobility and ease ofattachment of the cover apparatus to the front of the fireplace or thefireplace opening will allow for removal (including detachment,retraction, rolling up or compression) of the cover apparatus once thefire is self perpetuating. This removal of the cover apparatus allowsone to see the full frontal opening of the fireplace. The advatages ofsuch an apparatus is simplicity, no retrofitting and no change ofappearance of the fireplace once the apparatus has been removed orretracted.

SUMMARY OF THE INVENTION

[0015] Our invention provides a novel and unobvious apparatus whichhelps to improve air flow to the fuel in a fireplace. This apparatusinvolves an easily attachable or positioned and easily removable orretractable cover apparatus which can be placed over the front openingof the firebox of the fireplace. This cover is placed and sized suchthat it covers the upper portion of the front opening of the firebox andaccordingly forces the air flow through the lower portion of the frontopening which in turn increases the air flow to the fuel. This cover isespecially useful during the time period when the fire is being started.It will normally be either retracted or removed once the fire is selfperpetuating. By removing or retracting the cover apparatus thefireplace owners can enjoy seeing the full front opening of thefireplace.

[0016] In one embodiment of our invention the apparatus is a fireproofcover (for example a rectangular canvas cloth possibly covered with fireretardant material) which hangs down from a rod which in turn isattached to two or more hooks or other attachment devices over the frontopening of the fireplace. The cover is sized such that it covers the topportion of the front opening but not the lower portion. The cover ishung over the opening after the fire has been started and is beginningto draw air into chimney but before the fire is self perpetuating (orthe cover apparatus can be used to revive a fire that is beginning todie down). Normally but not necessarily the cover apparatus would beremoved once the fire is self perpetuating. This detachment orretraction of the cover would return a normal appearance to thefireplace (i.e. nothing obstructing the front opening of the fireplace).

[0017] This invention solves the problems with previous prior artbecause it is: (1) simple and inexpensive; (2) easy to retrofit; (3)does not change the appearance of the fireplace (except when it is inuse when starting or reviving a fire); and (4) does not involve themanual methods of fanning a fire such as a diaphram blower, fans, ornewspapers used as fans.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In the drawings:

[0019]FIG. 1 is front view of a fireplace with the cover apparatusattached above the opening of the fireplace but in a retracted (rolledup) position.

[0020]FIG. 2 is the same front view of the fireplace with the coversurface unrolled and hanging in front of the fireplace opening.

[0021]FIG. 3 is the same front view of the fireplace but there is adifferent cover apparatus which is standing on the hearth as opposed tohanging from above the opening of the fireplace.

DETAILED DESCRIPTION OF THE INVENTION

[0022] The embodiment of the invention shown in FIGS. 1, 2 and 3 shows astandard residential fireplace which has hearth 11 (it could also justbe called the floor or base), firebox 12, and front opening 20 which isdefined by the front perimeter walls 13. It has been observed byinventors that when making a fire in a fireplace such as is shown inFIG. 1 (or in fact any type of fireplace) that it is important to havemaximum air flow over or toward or through fuel 50 (in this case wood).It has further been observed that once a fire has been started and thechimney is drawing air that much of the air flow ends up not beinghelpful to the oxidation of fuel 50 but instead simply goes up thechimney or flue (not shown in these figures) through the upper portionsof front opening 20. In short, the air (with the vital oxygen) is wastedand never comes in contact with fuel 50 because of its upper level paththrough front opening 20 and out the flue. (This is despite the factthat grate 60 attempts to maximize the air flow on fuel 50 by raisingfuel 50 higher in firebox 12 and grate 60 also allows for air flow to gounderneath grate 60 since it is typically a series of open spacesdefined by bars of metal).

[0023] In order to maximize the air flow on fuel 50, persons over theyears have tried numerous methods as discussed in the Backgroundsection. As may now be easily understood from the description and thedrawings, inventors have determined that an easily removable orretractable cover apparatus will force air flow through the lowerportion of front opening 20 and into the lower portion of firebox 12 andonto or toward fuel 50. This is especially effective once the fireplacehas begun to draw. This is because once the fire has begun to draw ifone puts cover surface 41 over the top portion of front opening 20 thefireplace will continue to draw but all the air flow is forced throughthe much smaller opening at the bottom of front opening 20.

[0024] In fact, if the fire is drawing well there will be significantpressure on cover surface 41 since there will be low pressure on thebackside (i.e. in firebox 12) and higher pressure on the front side ofcover surface 41 (i.e. facing the room). This pressure differential actsto pull cover surface 41 toward firewall 12. If cover surface 41 iscanvas or cloth or some other easily rollable material the pressuredifferential may necessitate attaching support structures 70 onto coversurface 41 or incorporating support structures 70 into cover surface 41(as shown in FIG. 2). Support structure 70 can be any of a number ofwell known materials (metal, wood etc) and can be in the form of a rod,bar, slat, or webbing and so forth. The good news about the pressuredifferential is that it acts to pull cover surface 41 agaisnt the wallsand perimeter 13 which can minimize the leakage of air around coversurface 41 and force the great majority of the air flow through thelower portion of the frontal opening where it is most beneficial inoxidizing fuel 50.

[0025] There are a number of different ways in which cover surface 41can be placed over the top portion of front opening 20. In FIG. 1, thepreferred embodiment shows cover apparatus 40 attached to attachmentmeans 30. It could also be attached to a fireplace screen if the screenwas flush agaisn't front opening 20 (see the Experiments below). In FIG.1 attachment means 30 are simple hooks which have been anchored into thewall above fireplace front opening 20. Cover apparatus 40 is comprisedof cover surface 41 which has been rolled around rod 42. The ends of rod42 are attached to attachment means 30 (in a preferred embodiment it isvery easy to attach or detach cover apparatus 40 so that it installed(e.g. hung) and removed very quickly and easily such as would be thecase with the simple hooks shown as attachment means 30).

[0026]FIG. 2 shows cover apparatus 40 (which includes cover surface 41)unrolled, unfurled or pulled down such that cover surface 41 covers theupper portion of front opening 20. In the preferred embodiment one canalter the length of cover surface 41 hanging over front opening 20 tomodify air flow and direction into firebox 12. This unrolling, pullingdown or unfurling of surface 40 can be done by methods identical to theextremely well known action of pulling down window blinds and by usingidentical mechanisms (e.g. rolling and unrolling a flat sheet orcompressing, extending a pleated sheet in a concertina type action oreven the use of slitted materials similar to those used in Levolar™window blinds). For example, the unrolling, pulling down or unfurlingaction could be accomplished either manually by simply turning rod 42 ina circular motion or if cover apparatus 40 is designed like the wellknown window blinds then this unrolling could also be accomplished bypulling down on surface 41 until cover surface 41 covers the desiredupper portion of front opening 12. In short, there are numerous ways inwhich surface 41 could be placed over front opening 20 and they will bewell known to those skilled in the art.

[0027] It is important that cover surface 41 and support means 70 aresized such that they extend beyond perimeter 13 and out onto the wallbeyond perimeter 13 because the pressure differential will tend to bowor pull cover surface 41 in towards firewall 12 and accordingly coversurface 41 and support(s) 70 needs to be somewhat larger than thehorizontal dimension of front opening 20. Also it may be desirable tomake support(s) 70 out of heavy material so that they keep cover surface41 pulled taut so that the pressure differential does not pull coversurface 41 into firebox 12.

[0028] In a less preferred embodiment, cover apparatus 40 could bedesigned such that it does not roll up into a cylinder as shown inFIG. 1. It is possible that cover apparatus 40 could simply bepermanently as shown in FIG. 2, where surface 41 is not rolled aroundrod 42. In such a case cover apparatus 40 would simply be attached toattachment means 30 and would always be in an unrolled or rectangularconfiguration. In this configuration, cover surface 40 might even berigid (as shown in the embodiment of the FIG. 3). However a rigidapplication is probably not a preferred embodiment since it would takeup more space then the embodiment where cover surface 41 is able to berolled up onto rod 42. In the “window blind” embodiment cover apparatus40 is a relatively compact cylinder that is able to be storedunobtrusively near the fireplace for frequent use.

[0029]FIG. 3 shows another less preferred embodiment of cover apparatus40 which does not involve hanging cover surface 41 from attachment meansabove the fireplace opening. In FIG. 3 surface 41 is rigid and issupported by legs 45 which set on hearth 11. In this instance surface 41and legs 45 can be any of a number of different well known metallic orfireproof materials (fireproofing is probably preferred but is notstrictly necessary as applicants actually used newspaper agaisn't ascreen in proof of concept experments detailed below and the newspapershad small burn marks but never caught entirely on fire). The embodimentshown in FIG. 3 is also not preferred because it is difficult to changethe amount of the upper portion of front opening 12 which cover surface41 is covering.

EXPERIMENTS

[0030] Proof of concept experments were run in a standard residentialfireplace with an upwardly extending flue and chimney and which had astandard metallic screen which laid flush agaisn't the front opening ofthe fireplace. The fireplace front opening was approximately 26 incheshigh and approximately 46 inches wide. The screen could be drawn shut sothat it covered the entire front opening of the fireplace. Wood wasplaced on a standard metal grate. Assuring that the flue was open to thechimney, we used scrap newspaper underneath the grate to attempt tolight the slightly damp wood (it had been stored outside without cover)on top of the grate. Using standard methods we were successful ingetting the .chimney to draw air flow into it and we were successful ingetting the wood partially burning but not self perpetuating (thesemoderate successes were attained with great effort by continuing to feednewspaper under the grate and fanning the newspaper and wood).

[0031] In proof of concept of the invention, we then proceeded to takeportions of newspaper and put them agaisn't the front opening screen.The pressure differential caused by the draw from the chimney was suchthat the newspaper (in single sheet thicknesses) was forced agaisn't thescreen and did not have to be held in place agaisn't the vertical screenby hand. Experimenting with placement of the newspapers we found that bycovering the upper portion of the front opening screen and leaving thebottom portion uncovered that comparatively large quantities of air (andobviously oxygen) flowed through the bottom portion of the screen andonto the wood. The effect was dramatic and could even be heard as therush of air flowed past the newspapers and onto the burning wood. In amatter of seconds the wood was burning more intensely. In a matter of1-2 minutes the fire (which previously had been difficult to start) wasroaring and self perpetuating. We found that the invention worked bestby covering roughly the upper two thirds (16 to 18 inches) or the upperthree quarters (19-21 inches) of the screen over the front opening(although it is entirely possible that in other fireplaces with othergeometries and designs that other ratios may prove more effective—inaddition, the effect is apparent, but not optimized, with almost anyamount of coverage of the upper portion of the fireplace opening). Afterthe fire becomes self perpetuating it was very easy to remove thenewspapers and enjoy the full frontal view of the fireplace.

[0032] This experiment was repeated a handful of times over a 3-4 dayperiod and in each experiment it worked quite well in starting or inreviving a fire.

[0033] An invention has been described that provides advantages in theart of fireplace cover apparatuses. Although the preferred embodimentshave been described specifically with regard to detail, it should benoted that many details my be changed without departing from the scopeof the invention as it is defined in the following claims.

We claim:
 1. In combination with a fireplace having a hearth or floor, afirebox chamber exhausting upwardly to a chimney, and a front opening; acover apparatus comprising: a cover surface designed to cover the upperportion of the front opening which cover surface is easily removablefrom the front opening.
 2. The cover apparatus of claim 1, wherein saidcover apparatus is attached above the front opening.
 3. The coverapparatus of claim 2, wherein the cover surface may be rolled up intothe cover apparatus or compressed back toward the cover apparatus. 4.The cover apparatus of claim 3, wherein the length of the cover surfacecovering the front opening of the fireplace may be altered.
 5. The coverapparatus of claim 1, wherein the cover surface has supports which aresufficient to prevent a pressure differential from pulling the coversurface into the firewall.
 6. The cover apparatus of claim 1, whereinsaid cover apparatus is attached to a fireplace screen placed agaisn'tthe front opening of the fireplace.
 7. The cover apparatus of claim 1wherein, the cover surface has legs setting upon the hearth or floor. 8.A method of increasing the intensity of a fire in a fireplace having afront opening; comprising covering the upper portion of the frontopening of the fireplace with a cover apparatus which can be easilyremoved from the front opening of the fireplace once the fire has becomeself perpetuating.